Digital ink technology enables a user to write and draw on the touch-sensitive screen of a handheld PC or other writing tablet with a stylus or other pointing device, providing a convenient means for applications to accept input from a user without using a keyboard. For a user, taking notes or drawing sketches using digital ink technology is very much like writing or drawing on paper.
Contemporary digital ink technology is capable of extracting a variety of information from an ink trace that a user makes using digital ink technology, including vector, timing, coordinates, angle of the stylus, and additional information. The digital ink information may be provided to an application, and may be used for many purposes, such as for handwriting recognition. The digital ink information may also be used for improving the way handwriting is displayed, including providing higher resolution, editing, smoothing, and alteration of individual elements, for example.
One problem with digital ink technology is that the files generated from a user's handwriting are typically large. Generally, the file consists of a sequence of points where the user has contacted the writing surface, as well as additional digital ink information such as discussed above. The size of the files can be a problem, for example, where the digital ink file needs to be transmitted, where a large number of the digital ink files need to be stored, or where the digital ink file needs to be processed, such as for display or handwriting recognition.
Contemporary technologies exist for compression of digital ink information. However, typically so much information is lost during compression that the compressed file does not accurately represent the shape information of the original ink trace, which may result in poor display or recognition.
Another problem with digital ink technology is in display. Often, even if the original ink data is used, it is difficult to display a representation of the actual ink trace because of the resolution limitations of a monitor or other display device. The sequence of points representing the ink trace may not properly align with the pixels on the monitor, and present technologies do not provide a feature that permits the view on the monitor to accurately represent a visual presentation of an item (e.g., point or portion of a line) in a position that does not align with a pixel on the display.
Often, contemporary display software includes antialiasing effects, which provide different graying levels for pixels on a display in an attempt to display a representation of an item that should be located only partly on the grayed pixels. However, when lines or curves are rendered with an antialiasing technique, the rendered image of these lines and curves has a ripple contour, which makes rendered shapes have different widths at different parts. Having different widths is caused by the variance of gray levels value along the line or curve. This effect is most obvious when the line or curve being rendered is relatively long. In lines that are nearly horizontal or vertical, the rippled effect is particularly pronounced.